The good news is 90 percent of American children are vaccinated by the time they reach kindergarten. However, a new report by the Institute of Medicine shows that many parents don't follow the recommended time schedule for their children's immunizations, which can compromise their effectiveness.

Children are supposed to receive 24 immunizations, given in one to five shot injection groups during a pediatric visit, by the time they are 2. If they do so, studies have shown that kids can benefit from fewer illnesses, deaths and hospital stays. All the vaccines are tested for safety both on their own and in conjunction with all the other vaccines that are given at the same time. The review did not find evidence that vaccines are in any way linked to autoimmune diseases, asthma, hypersensitivity, seizures, child developmental disorders, learning or developmental disorders or attention deficit or disruptive disorders.

Researchers fear that parents aren't made aware about the details of the schedule, including the number of shots needed, the frequency, the timing, the order and the age the vaccines are given. This makes them less likely to find it important to stick to the recommended plan.

"The Institute of Medicine is always asked to review large amounts of data, and the committee that they put together consists of individuals of very, very high ranking statuses -- experts in the field, professionals pediatrician, people who take care of children as well as a parents. People need to pay attention to their recommendations," Cleveland Clinic Pediatrician Dr. Elaine Schulte told CBSNews.com. She was not involved in the recommendations.

While the IOM is confident that the vaccines are safe for children, one problem is that studies can't exactly show the potential problems of not vaccinating or not following the schedule because of undue risk to the test subjects. Though randomized controlled trials could work, the chances the children who are not vaccinated in time might get these deadly yet preventable diseases is too high. This pushes researchers to chose parents who opt not to vaccinate for a variety of reasons -- about 1 percent of the population -- but then the group isn't exactly a random cohort. Most of these parents are of a certain ethnic or racial group, and tend to be different socio-economically and genetically than the rest of the population.

"We don't know what would happen, but as a professional and as a parent, I don't want to find out what would happen if we get casual (with the vaccination schedule)," Schulte said.

"There's been plenty of examples of vaccine-preventable diseases that have surfaced," she added. "It's been frequently discovered that folks involved in these outbreaks are folks who were not immunized or not immunized in time."

In order to do further research on the efficacy and possible dangers of vaccines, the researchers advocated for newer and bigger data collection systems. Upcoming programs include the Sentinel Initiative program being developed by the U.S. Food and Drug Administration, which will track the safety of approved drugs and medical products, and the Post-License Rapid Immunization Safety Monitoring Program, which will collect a large amount of health data so researchers can take a closer look at vaccine exposures and adverse events.

For now, they approved of the Vaccine Safety Datalink (VSD), which contains data on more than 9 million people in nine participating managed care organizations in eight states. VSD allows medical professionals to see if someone was given immunizations on schedule and any diagnoses, medical procedures and outcomes they might have had. It also collects data on race, age, gender and other factors that can help researchers analyze how certain factors may affect a particular group's health. For example, researchers are using data from VSD to look at a certain population of children in the Kaiser Permanente Colorado system that are undervaccinated.

In addition to only showing a small sampling of states, VSD only tracks a small percentage of low-income and minority people in the U.S. The authors hope that the U.S. Department of Health and Human Services will help promote VSD and encourage other health care providers to join so the data can be representative of the U.S. population.

The American Academy of Pediatrics said in a statement it supported IOM's findings.

"This report is unique in that it is the first attempt to examine the entire childhood immunization schedule as it exists today. The IOM committee found no evidence of major safety concerns when following the schedule, and in fact confirmed that following the schedule strongly reduces the risk of disease," said Dr. Thomas K. McInerny, president of the American Academy of Pediatrics. "Pediatricians and parents have the same goal of giving children the best start in life, and vaccines play an essential role in protecting children from harm."